Integrated passive devices are used in mixed-signal circuits, analog circuits, radio frequency (RF) circuits, dynamic random access memories (DRAMs), embedded DRAM circuits, logic operation circuits, and the like. Integrated passive devices include capacitors, inductors, transformers, resistors, and the like.
The formation of the integrated passive devices may be similar to the processes for forming active devices, wherein starting from a silicon substrate, dielectric layers are formed layer by layer, and metal lines and vias are formed in the dielectric layers. Passive devices are also formed in the dielectric layers.
The conventional integrated passive devices often suffer from low performance that cannot meet the requirement of RF circuits. For example, the Q-factors of the capacitors in the conventional integrated passive devices are low, and the bandwidths of the inductors are narrow. The low performance of the integrated passive devices may be caused by Eddy currents in the respective substrates.